Toxicological effects of cadmium and lead during pregnancy in tobacco smoke, secondhand smoke, and thirdhand smoke



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TOXICOLOGICAL EFFECTS OF CADMIUM AND LEAD DURING PREGNANCY -- IN TOBACCO SMOKE, SECONDHAND SMOKE, AND THIRDHAND SMOKE

by

Fangchen Yu



B.S, China Agricultural University, China, 2015

Submitted to the Graduate Faculty of

Environmental and Occupational Health

Graduate School of Public Health in partial fulfillment

of the requirements for the degree of

Master of Public Health

University of Pittsburgh

2017






UNIVERSITY OF PITTSBURGH

GRADUATE SCHOOL OF PUBLIC HEALTH

This essay is submitted

by

Fangchen Yu


on
April 28, 2017

and approved by


Essay Advisor:

James Peterson, PhD ______________________________________

Associate Professor

Department of Environmental and Occupational Health

Graduate School of Public Health

University of Pittsburgh

Essay Reader:

Kurt E. Beschorner, PhD ______________________________________

Research Assistant Professor

Department of Bioengineering

Swanson School of Engineering

University of Pittsburgh



Copyright © by Fangchen Yu

2017

A
James Peterson, PhD
TOXICOLOGICAL EFFECTS OF CADMIUM AND LEAD DURING PREGNANCY -- IN TOBACCO SMOKE, SECONDHAND SMOKE, AND THIRDHAND SMOKE

Fangchen, Yu, MPH

University of Pittsburgh, 2017

BSTRACT

Tobacco smoking during pregnancy is a major public health concern. It is well known that smoking before and during pregnancy can cause illness and death to both mothers and infants; furthermore, smoking after delivery can affect infants’ health conditions via secondhand smoke (SHS) and thirdhand smoke (THS) exposure. Total tobacco smoke exposure is the cumulative involuntary exposure to tobacco smoke pollutants during and after smoking, which means that secondhand smoke and thirdhand smoke are also dangerous risk factors that could affect pregnant women and their babies. This essay introduces some basic information about the adverse health effects of tobacco smoke, secondhand smoke, and thirdhand smoke. Furthermore, this essay focuses on two chemical components of tobacco – cadmium and lead, comparing the specific health effects they could lead to in pregnant women and infants through exposure to firsthand (direct) smoke, secondhand smoke, and thirdhand smoke.

TABLE OF CONTENTS


TABLE OF CONTENTS v

List of tables vi

List of figures vii

1.0 Introduction 1

2.0 Review of the relevant literature 3

3.0 Analytical Section 10

4.0 Conclusion 17

BIBLIOGRAPHY 21

BIBLIOGRAPHY 21

List of tables


Table 1. Comparison of Secondhand Smoke and Thirdhand Smoke 7

Table 2. Concentration range of heavy metals in cigarette and snuff samples (mg kg-1) 13

Table 3. Comparison of Lead and Cadmium 15

List of figures


Figure 1. Prevalence of smoking before pregnancy, and after delivery* by year PRAMS, United States, 10 sites**, 2000-2010 11


  1. Introduction


Exposure to tobacco smoke during pregnancy remains a great public health concern all over the world. In spite of development of strategies and policies to reduce tobacco smoking, the population of smokers still remains very large. In particular, the prevalence of smoking during pregnancy in the U.S. between 2000 and 2010 didn’t significantly decreased28. Tobacco smoke can lead to many adverse health effects in both pregnant women and infants. Maternal tobacco smoking has been associated with ectopic pregnancy, placental abruption, preterm delivery, low birth weight, stillbirth, perinatal morbidity and mortality, and sudden infant death syndrome (SIDS)7,8,9,10.

Exposure to firsthand (direct) smoke is not the only way in which the contaminants contained in tobacco products can adversely impact the human body. Secondhand (indirect) smoke and thirdhand (residual) smoke are also produced by tobacco, and these two forms can persist for a much longer duration than firsthand smoke. Furthermore, the chemicals contained in tobacco smoke gases may undergo some physical and chemical transformations during that extended period of time to create further toxicants13.

There are over 7,000 chemicals identified in tobacco smoke and over 70 of them are cancer-causing chemicals1. This essay focuses on two of these toxicants – lead and cadmium. It has been suggested that, in unpolluted areas, smoking may be the main source of exposure to some heavy metals19, such as lead and cadmium. In other words, pregnant women and their babies may be exposed to lead and cadmium if the women smoke themselves, or are exposed to secondhand/thirdhand smoke even though they are not exposed to any other environmental or/and occupational sources. Many studies have confirmed that even relatively low levels of lead and cadmium exposure might pose a health risk19,31,32. Lead and cadmium affect many target organs in the human body, such as the brain, kidney, and immune system. Furthermore, infants are more sensitive to these heavy metals than adults18. Clearly, from a Public Health perspective, we should be concerned about exposures to the toxicants (including lead and cadmium) contained in tobacco products during pregnancy.

The purpose of this essay is to attract public attention to the impacts of firsthand, secondhand, and thirdhand smoke to pregnant women and their babies; furthermore, this essay also emphasizes that these three forms of smoke can become exposures to some heavy metals (such as lead and cadmium) and lists the adverse health effects of two specific toxicants contained in tobacco products – lead and cadmium.


  1. Review of the relevant literature

    1. Maternal tobacco smoke


Smoking during pregnancy remains a significant public health concern for both maternal health and infant development. Although tobacco smoking is an established risk factor for both fetus and pregnant women, there still remains a great deal unknown about the biological mechanisms of how smoking leads to health problems in pregnant women and how it affects fetal development.

In 2015, about 15 in every 100 U.S. adults aged over 18 years (15.1%) smoked cigarettes, in other words, in the United States approximately 36.5 million adults currently smoke cigarettes. By gender, more than 13 of every 100 adult women (13.6%) currently smoke based on the information provided by the United States Center for Disease Control and Prevention (CDC)2. Moreover, more than 400,000 babies born in the U.S. every year exposed to tobacco chemicals before birth due to maternal smoking5. According to the results of a survey from the International Child Care Practices Study, an average of 22% mothers and 45% fathers were smoking when their child was born3. A survey undertaken in 24 states in the U.S. in 2011 from the Pregnancy Risk Assessment and Monitoring System (PRAMS) concluded that approximately 10% of women were smoking during the last 3 months before delivery4.



    1. Related health effects of tobacco smoke


Studies have suggested that smoking affects fertility in women – smoking affects estrogen and other hormones and can make it more difficult for women to become pregnant, or even never become pregnant5,6. What’s more, smoking could lead to miscarriage and ectopic pregnancy, a condition in which the fertilized egg fails to attach itself inside uterus, doubling the risk of abnormal bleeding during pregnancy and delivery7. Compared to non-smoking women, those who smoke prior to pregnancy have approximately 30% higher odds of being infertile. Women who smoke during pregnancy double the risks of premature rupture of membranes, placental abruption (separation from uterus), and placenta previa (obstruction of cervix) during pregnancy8.

There is substantial evidence that maternal tobacco smoking will lead to a number of adverse developmental consequences to the fetus and long-term adverse health effects to the offspring. Maternal tobacco smoking has been associated with preterm delivery, low birth weight, stillbirth, perinatal morbidity and mortality, sudden infant death syndrome (SIDS)9,10. The long-term health consequences to the newborns include behavioral problems, attention deficit disorders, and antisocial behavior11. According to the United States Center for Disease Control and Prevention (CDC), babies born to women who smoke during pregnancy have about 30% higher odds of being born prematurely, and are more likely to be born with low birth weight. Furthermore, they are 1.4 to 3.0 times more likely to die of SIDS8. Tobacco smoke also damages the developing brain and lung tissues of the fetus leading to abnormal development of the lungs25.


    1. Secondhand smoke, Thirdhand smoke


According to the Untied States Center for Disease Control and Prevention (CDC), the definition of secondhand smoke (SHS) is “the combination of smoke from the burning end of a cigarette and the smoke breathed out by smokers.” Secondhand smoke is also known as “environmental tobacco smoke(ETS)” and its inhalation referred to as “passive smoking”5. Like firsthand smoke, secondhand smoke also contains more than 7000 chemicals and the National Toxicology Program estimated that at least 250 of those could be toxic, or carcinogenic (including nicotine, carbon monoxide, benzene, cadmium, etc.); furthermore, there is no “safe” level of exposure5. Compared to the smokers’ inhalation, secondhand smoke contains lower doses of the same toxicants, therefore, secondhand smoke exposure during pregnancy should have similar but less severe effects24. According to the definition of secondhand smoke, secondhand smoke is a combination of the mainstream smoke and side-stream smoke. About 85% of the smoke present in a confined space, such as a room is constituted by side-stream smoke; moreover, the concentrations of the toxicants in the side-stream smoke are higher than the concentrations in the mainstream smoke24. The United States Center for Disease Control and Prevention estimated that about 90% of nonsmokers in the United States are exposed to secondhand smoke and, since 1964, that approximately 2,500,000 nonsmokers have died because of the health problems triggered by secondhand smoke5.

As with inhaled smoke, maternal exposure to secondhand smoke is associated with premature death, low birth weight, SIDS, and diseases to both children and their mothers5. Babies who breathe secondhand smoke after birth can have weaker lungs than unexposed infants25.


Thirdhand smoke (THS) is a newly described health risk that remains poorly understood. It is defined as a toxic residue that remains after the tobacco has been extinguished12. Thirdhand smoke contains a mixture of semi-volatile compounds found in secondhand smoke that have settled on surfaces of an indoor space and are later re-emitted into the air12. The residues releasing thirdhand smoke can remain in peoples’ clothes and hair, and in furniture13. Once tobacco smoke pollutants adhere to surfaces, they become difficult to remove and remain in the environment. Compared to secondhand smoke, thirdhand smoke will persist in the atmosphere for a longer period of time, and the smoke will react with oxidants and other compounds in the environment to create new carcinogens not seen in the tobacco smoke13. Because thirdhand smoke is particularly associated with the less volatile components of tobacco smoke, we should be very concerned that it may be more concentrated in heavy metal toxicants (like cadmium and lead) than firsthand or secondhand smoke.

Thirdhand smoke can enter the human body by ingestion, by inhalation, and via skin. Both pregnant women and infants are at risk from thirdhand smoke. However, as babies are more likely to be close to contaminated surfaces (for example, since they cannot walk, they may spend more time in contacted with contaminated surfaces, such as furniture and carpet) and considering their behavior (crawling over, touching, and putting things in their mouths), thirdhand smoke is expected to be more dangerous to infants than adults. The health effects of thirdhand smoke has been explored in recent years. Thirdhand smoke can cause DNA damage in human cells; and in animal experiments, thirdhand smoke has a detrimental effect on prenatal lung development, and can adversely affect multiple organ systems, such as respiratory problems later in life23.


Table 1. Comparison of Secondhand Smoke and Thirdhand Smoke






Secondhand Smoke (SHS)

Thirdhand Smoke (THS)

Definition

SHS is a mixture of the side-stream smoke and the mainstream smoke exhaled from the lungs of smokers.

Thirdhand smoke consists of residual tobacco smoke that remains on indoor surfaces after tobacco has been smoked.

Chemical Components

SHS contains more than 7,000 chemicals, the major toxic chemicals include nicotine, carbon monoxide, ammonia, hydrogen cyanide, cadmium, sulfur dioxide, and some other toxicants.

THS reacts with ozone and nitrous acid to produce secondary highly carcinogenic pollutants14, such as formaldehyde, and tobacco-specific nitrosamines (TSNAs). According to the New York Times34, 11 carcinogenic compounds that could be in THS include: Hydrogen cyanide, butane, toluene, arsenic, lead, carbon monoxide, and polonium-210.

Duration of Exposure

SHS takes at least two hours to dissipate.

Not fully studied, THS can linger on surfaces for months15.

Exposure

Involuntary inhalation of side-stream and exhaled mainstream smoke.

Involuntary inhalation, ingestion, or dermal uptake of THS pollutants in the air, in dust, and on surfaces.
    1. Cadmium


Cadmium (Cd) is a heavy metal widespread in the environment and understudied as an environmental toxicant. Tobacco smoke is one of the primary sources of environmental exposure to cadmium for smokers. Cigarettes manufactured in the United States contain 1-2 μg cadmium per cigarette and 10% of this amount is inhaled via inhalation by smokers16. One cigarette can increase the blood cadmium concentration level by approximately 0.1-0.2 μg /L. There is evidence that smokers have about 4-5 times higher blood cadmium concentrations, and twice as high kidney cortex cadmium concentrations as nonsmokers16. Cadmium is easily absorbed by human and animals, it can retain and accumulate in organs and tissues for a relatively long period of time17 -- the biological half-life of cadmium is approximately 30 years.

Cadmium is a nephrotoxin, neurotoxicant, osteotoxicant, and carcinogen, it can lead to many health conditions, including hone disease, prostate cancer, breast cancer, renal cancer18, etc. Both human and animal studies point out that cadmium affect cardiovascular, kidney, and especially, skeleton. Cadmium exposure may lead to skeletal damage (osteoporosis) and women have a greater risk of developing cadmium-induced osteoporosis26. To fetus, a number of studies indicate that maternal cadmium burden is associated with many adverse health effects, including low birth weight, short birth length, and small head circumference. Furthermore, cadmium exposure is associated with intelligence problems and learning disorders to children27.


    1. Lead


Lead (Pd) is a heavy metal and a ubiquitous environmental toxicant which is specifically a neurotoxicant. It is well known that even low-level lead exposure causes lasting adverse health effects on children’s neurodevelopment including low intelligence quotients (IQ), attention span, learning disability, mild mental retardation and behavioral abnormalities20. In recent years, the researchers have pay more attention to the effects of prenatal exposure. There seem to be two particular issues associated with lead and pregnancy. First, the fetus is highly sensitive to the exogenous sources of exposure; second, lead stored in bones from previous is mobilized during pregnancy and lactation, which provides an endogenous exposure, releasing the toxicant into maternal blood and breast milk21. Since bone lead stores persist for decades, even in the case of women who quit smoking before pregnancy, the endogenous exposure may still persist.

The major adverse health effects of lead on the adult human body appear in heme biosynthesis, erythropoiesis, kidneys, nervous system and blood pressure (gestational hypertension in pregnant women)22. On the fetus, lead crosses the placenta to affect the developing fetus. It has been demonstrated that elevated lead exposure during pregnancy can lead to preeclampsia, poor fetal growth, and impaired neurodevelopment22.


  1. Analytical Section

    1. Smoking trends during pregnancy in the U.S.


Although the total number of women smokers has been declining in the U.S., the rate is slowing. According to the trend for maternal tobacco smoking (Figure 1), the prevalence of smoking during the 3 months before pregnancy had a significantly increase during 2008-2009, then the rate decreased in 2010. The prevalence of smoking during the last 3 months of pregnancy decreased significantly from 13.3% in 2000 to 12.3% in 2010. The prevalence of smoking approximately 4 months after delivery keep decreasing during 2000-2010 (from 18.6% in 2000 to 17.2% in 2010)28.

In summary, during 2000-2010, the prevalence of smoking before pregnancy did not change significantly; both the prevalence of smoking during pregnancy and after delivery had moderately decrease. However, none of the PRAMS sites for any year between 2000 and 2010 reached the Healthy People 2020 goal28 — reducing the prenatal smoking prevalence to 1.4%.


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Figure 1. Prevalence of smoking before pregnancy, and after delivery* by year PRAMS, United States, 10 sites**, 2000-2010

(CDC, 2013)

*Smoking before pregnancy was defined as smoking 3 months before pregnancy on the basis of the PRAMS survey. Smoking during pregnancy was defined as smoking during the last 3 months of pregnancy on the basis of the PRAMS survey. Smoking after delivery was defined as smoking approximately 4 months after delivery on the basis of the PRAMS survey.

**Data aggregated for 10 PRAMS sites (Alaska, Arkansas, Colorado, Hawaii, Maine, Nebraska, Oklahoma, Utah, Washington, and West Virginia) with data available for all years.
In 2010, more than half of pregnancy women (54.3%) quit smoking during pregnancy28, but there were still as many as half women keep smoking during pregnancy, which could cause infant morbidity and mortality.

Although the data of secondhand smoke exposure to pregnant women in the U.S. is incomplete, according to a study from CDC29, secondhand smoke exposure in the U.S. has been significantly reduced from 1999 to 2012 among nonsmokers aged over 3 years. The percentage change of nonsmokers with serum cotinine levels (used to represent secondhand exposure) was 51.8% – from 52.5% during 1999-2000 to 25.3% during 2011-2012. In female, the percentage of nonsmokers with serum cotinine levels was declined from 47.5% during 1999-2000 to 23.3% during 2011-2012, the percentage change was 50.9%. Overall, secondhand smoke exposure has significantly decreased in recent years, however, many people are still exposed to secondhand smoke in the U.S.


    1. Cadmium and Lead


In the U.S., lead exposure to pregnant and lactating women remains a great public health concern. According to data from the National and Nutrition Examination Survey, 2003- 2008, approximately 1% of women of childbearing age (15-44 years) have blood levels greater than or equal to 5 μg/dL – a reference blood lead level from CDC at which public health actions are recommended to be initiated35. Generally, the lead level in human body is represented by blood lead level.

The general methods to evaluate cadmium levels in the human body is to measure the concentration of cadmium in blood and urine. The results of these two methods represent different exposures to cadmium – the cadmium value in blood represents the current cadmium exposure, whereas the concentration of cadmium in urine reflects lifetime cadmium exposure16. Both these two methods were used in studies associated with cadmium effects on pregnant women and infants.


Table 2. Concentration range of heavy metals in cigarette and snuff samples (mg kg-1)



Samples

Pb

Cd

Dorchester

1.00-3.00

0.02-0.02

Moritz

0.85-0.88

0.18-0.18

Benson and hedges

0.60-0.80

0.51-0.51

Marlboro

2.10-2.10

0.35-0.44

Yes

0.71-0.90

0.56-0.56

Sweet menthol

1.77-2.77

1.64-1.83

Lemon and butter

1.36-3.14

2.11-2.11

Rothmans

0.14-0.14

0.14-0.14

Green sport

0.12-0.12

2.00-2.00

White London

2.22-2.25

0.23-0.23

Snuff

3.09-3.10

3.55-3.55

(Vincent A, Steven O, Felix E, et al. 2011.)
In ten different brands of cigarettes and snuff (Table 2) the total range of concentrations found for lead was 0.60-3.10 mg kg-1, and the total range of concentrations found for cadmium was 0.02-3.55 mg kg-1 36. The results demonstrate that while both lead and cadmium are contained in the tobacco products, the concentrations of these toxicants differ by an order of magnitude between brands. Moreover, as snuff has the highest concentration of both lead and cadmium, people who use snuff should be more susceptible to heavy metal-related diseases than cigarette smokers.
According to the results of one study published in 200819, smoking 20 cigarettes per day result in an inhalation of 2-4 μg cadmium and 1-5 μg lead, or even more. Moreover, this study concluded that there was a significant association between cadmium content in the cigarettes and the amount its release into the smoke. Moreover, the participants in this study who smoked high cadmium concentration cigarettes had higher blood cadmium concentration than participants smoked other cigarettes. A previous study published in 1992 also concluded that active smoking made smokers have much higher blood cadmium concentration30. As for lead, smokers had a 29% increase in blood lead concentration than nonsmokers. In women, smoking women had a 26% increase in blood lead concentration than the non-smoking ones19. Research focused on the reduction of cadmium exposure in the U.S. published in 201236 concluded that urine concentrations dramatically decreased during 1988-2008. Reduction in smoking rate was a crucial factor driving the lowering of urine cadmium over the past two decades. Among “ever smokers” (i.e. people who have ever been smoked), 17.1% of the observed loss of urine cadmium was due to the changes in smoking variables when comparing fully adjusted models with and without smoking variables. Among never smokers, when comparing fully adjusted models with and without cotinine (a marker of secondhand exposure), 15.6% of the adjusted urine cadmium concentrations lowering was apparent in the results. That is, the data indicated that secondhand smoke was a key factor driving the reduction of urine cadmium concentrations among nonsmokers36. Therefore, changes in smoking variables such as changes in smoking status, cumulative dose, secondhand smoke, and changes in cigarette composition over time all advance the reduction of urine cadmium concentrations.
As early as 1988, an association between blood lead concentration and secondhand smoke had been reported31. A recently published study in 2012 also indicated that secondhand smoke may increase blood lead levels among U.S. chidren32. As to the association between secondhand smoke and cadmium level, a Korean study published in 2015 concluded that there was a high positive correlation between the duration of secondhand smoke exposure and blood cadmium level33.

About ten years ago, the concept “thirdhand smoke” was introduced to the public. Compared with the researches focus on tobacco smoke and secondhand smoke, the amount of thirdhand smoke researches and the achievements are both less than those to the researches focus on tobacco smoke and secondhand smoke. The data of lead and cadmium in thirdhand smoke is scarce, however this is a new consideration to bring to the problem.



Table 3. Comparison of Lead and Cadmium




Lead (Pb)

Cadmium (Cd)

Amount of absorption

(based on 20 cigarettes per day)



1-5μg19

2-4μg19

Target organs

Brain, kidneys

Kidneys, bone, and lungs

Pregnant women

Tobacco smoke/Secondhand smoke health effects

Affects hem biosynthesis, erythropoiesis, kidneys, nervous system and blood pressure

Causes cardiovascular, kidney, and hone disease

Thirdhand smoke health effects

Data remain scarce

Infants

Tobacco smoke/Secondhand smoke health effects

Causes preeclampsia, poor fetal growth, and impaired neurodevelopment

Low birth weight, short birth length, and small head circumference

Thirdhand smoke health effects

Data remain scarce



  1. Conclusion


First of all, tobacco smoking remains as a critical public health problem, not only because of the great number of smokers all over the world, but also the problems can active smoking bring to the nonsmokers – secondhand and thirdhand smoke. Nowadays, many nonsmokers are exposed to secondhand and/or thirdhand smoke, and both of them are potential risk factors to health. Pregnant women are especially vulnerable to tobacco smoke, since the chemicals contained in tobacco products can lead to various adverse health effects to pregnant women and their babies. Based on the smoking trends of pregnant women in the U.S. from 2000 to 2010, the prevalence of smoking during pregnancy did not significantly changed during this period of time28. Moreover, some women start or relapse smoking after delivery. Smoking after delivery not only affects the mothers’ health conditions, but also affect the infants.

Secondhand smoke exposure has been decreased in recent years, however, there are still many people exposed to secondhand smoke. During 2011-2012, 25.3% nonsmokers in the U.S. were exposed to secondhand smoke29. Since 1964, that approximately 2,500,000 nonsmokers have died because of the health problems triggered by secondhand smoke5 in the U.S. These facts indicate that tobacco smoke also endanger nonsmokers. Therefore, tobacco control strategies are demanded to protect both smokers and nonsmokers. There were many tobacco control strategies adopted during the last few decades; for example, awareness campaigns, 100% smoke-free policies, increasing tobacco price through taxation, etc. These efforts are promising. Although most people have become aware of the negative health effects smoking produces in humans, there are still a large number of people who keep smoking, even when they themselves are pregnant. Specifically, the prevalence of quit smoking during pregnancy was 54.3% in 2010 based on the data provided by CDC28; in other words, there were still approximately half of the pregnant women keep smoking during pregnancy.

Many compounds in tobacco are carcinogens, all of which do harm to humans, not just lead and cadmium, some are known to be especially dangerous to fetus development. Therefore, the relatively small recent improvements in smoking habits associated with pregnancy (Figure 1) are frustrating. As to cadmium and lead, tobacco products can contain high levels of cadmium and lead due to the tobacco plant take up cadmium and lead from soil and concentrate them in leaves easily. However, there is no current law to control these and similar toxic heavy metals’ concentrations in tobacco products. According to the studies results provided above, both firsthand and secondhand smoke can create chronic lead and cadmium exposure to both smokers and nonsmokers. Lead and cadmium can accumulate in the human body, and it is well known that there is no “safe” level of exposure5. Therefore, it is difficult to see how regulatory bodies could begin to effectively legislate for the acceptable levels of cadmium and lead in tobacco products. Maybe more researches focus on this area in the future can improve the progress to build the law to control the contaminations in tobacco products.

Based on the results of one study published in 200819, there were no statistically significant correlations between cadmium or lead concentrations in the blood of smokers and the contents of these metals in cigarettes. The surprising lack of any correlations might be due to the fact that total uptake of contaminants from smoke not only depends on the specific metal contents in the tobacco products, but also on the intensity of individual smoking habits19, such as the duration of smoking and the amount of consumption.

The dose-response effects of both cadmium and lead levels need to be better characterized to enable delivery of appropriate public health prevention strategy, policy and individual healthcare to pregnant women and newborn infants. Trends in cadmium exposure and its resulting assimilation over time seem to not have been evaluated in any U.S. population36. Future surveys and researches need to collect data about some specific chemicals to understand the trends of some exposures and some further studies are demanded to improve the current knowledge about the association between some heavy metals and certain groups of people.

Although lead and cadmium exposure are known to be important potential risks to the fetus, to date, little emphasis has been placed on developing guidelines for prenatal health care providers and women of childbearing age. It appears that there are currently no national recommendations or guidelines published by any medically qualified group (e.g. obstetric, family practice, pediatric, or nursing) that cover lead and/or cadmium risk assessment and management during pregnancy and lactation.

There are important limitations to the existing body of research focusing on pregnant women. First of all, most of the data of smoke status has been collected via self-reported questionnaire. Some 54-56% of women report stopping or reducing smoking during pregnancy28 so there is a general recognition that it is undesirable. Consequently, the quantity of cigarettes they smoke might be overestimated, but is more likely underestimated, since the study population does not necessarily provide truthful responses when questioned. Moreover, studies of maternal smoking have not been done all over the world, only in some countries are there data available concerning maternal smoking. Studies from various parts of the world, especially where there may be cultural differences in attitudes toward smoking might be informative. Future studies may try to focus on the areas with paucity data, since the data and study results can help these areas to improve the management of tobacco products, develop regulations to protect people from firsthand, secondhand, and thirdhand smoke.

In the case of research focused on secondhand smoke, a great limitation is that we cannot eliminate the effects of exposure to other chemicals in the environment. However, as there is good reason to think that the effects of secondhand smoke are similar to those of firsthand smoke, but quantitatively less, it might be misleading to become overly concerned with this limitation. The greater worry at this time seems to be thirdhand smoke.

Thirdhand smoke is a newly described health risk, which has not been fully studied; there still remains much very basic information that is unknown about thirdhand smoke, such as the exact time it persists, the full list of potentially hazardous chemicals, etc. Furthermore, almost no research focus on the relationship between inorganic toxicants (like lead and cadmium) in thirdhand smoke and their negative health effects on pregnant women and their fetuses have currently been reported. Current studies pay more attention to nicotine in thirdhand smoke, future study may focus on if there are any heavy metals remain in thirdhand smoke and their possible health effects.
BIBLIOGRAPHY

1 Rodgman, A, Perfetti, T.A. (2013). The Chemical Components of Tobacco and Tobacco Smoke. Boca Raton (FL): CRC Press, Taylor & Francis Group.

2 Centers for Disease Control and Prevention. (2016). Cigarette Smoking Among Adults—United States, 2005–2015. Morbidity and Mortality Weekly Report. 65(44):1205–11

3 Nelson, E.A.S, Taylor, B.J. (2001). International Child Care Practices Study: infant sleep position and parental smoking. Early Hum. Dev., 64, 7-20.

4 Centers for Disease Control and Prevention. (2011). Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion.

5 U.S. Department of Health and Human Services. (2014). Let's Make the Next Generation Tobacco-Free: Your Guide to the 50th Anniversary Surgeon General's Report on Smoking and Health. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health.

6 U.S. Department of Health and Human Services. (2010). A Report of the Surgeon General: Highlights: Overview of Finding Regarding Reproductive Health. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health.

7 National Cancer Institute. (2014). Smoking, Labor, & Delivery: It's Complicated.

8 Centers for Disease Control and Prevention. (2004). Preventing Smoking and Exposure to Secondhand Smoke Before, During, and After Pregnancy.

9 Orton, S, et al. (2014). Longitudinal cohort survey of women's smoking behaviour and attitudes in pregnancy: study methods and baseline data. BMJ Open.

10 Cnattingius, S. (2014). The epidemiology of smoking during pregnancy: smoking prevalence, maternal characteristics and pregnancy outcomes. Nicotine & Tobacco Research. 6:125-140.

11 Lambe, M, Hultman, C, Torrång, A, MacCabe, J, Cnattingius, S. (2006). Maternal smoking during pregnancy and school performance at age 15. American Journal of Epidemiology. 17 (5): 524-530

12 Prokhorov, A.V; Calabro, K.S; Tamí-Maury, I. (2016). Nicotine and Tobacco Use Prevention among Youth and Families. Seminars in Oncology Nursing. 32 (3): 197–205.

13 Giraldi G, Fovi De Ruggiero G, Marsella LT, De Luca d'Alessandro E. (2013). Environmental tobacco smoke: health policy and focus on Italian legislation. Clin Ter. 164 (5): 429–435.

14 Drehmer J.E et al. Thirdhand Smoke Beliefs of Parents. (2014). Pediatrics. 133 (4): 850-856.

15 Matt, G.E, et al. (2004). Households contaminated by environmental tobacco smoke: sources of infant exposures. Tobacco Control. 13 (4):29-37.

16 McElroy, J. A, Shafer, M. M, Trentham-Dietz, A, Hampton, J. M, Newcomb, P. A. (2007). Urinary Cadmium Levels and Tobacco Smoke Exposure in Women Age 20-69 Years in the United States. Journal of Toxicology and Environmental Health, Part A. 70 (20): 1779-1782.

17 Kippler, M, Tofail, F, Gardner, R, Rahman, A, Hamadani, J.D, Bottai, M, Vahter, M. (2012). Maternal cadmium exposure during pregnancy and size at birth: a prospective cohort study. Environmental Health Perspectives. 120 (2): 284-289.

18 Vidal A.C, et al. (2015). Maternal cadmium, iron and zinc levels, DNA methylation and birth weight. BMC Pharmacology and Toxicology. 16 (1): p20.

19 Galażyn-Sidorczuk, M, Brzóska, M.M, Moniuszko-Jakoniuk, J. (2008). Estimation of Polish cigarettes contamination with cadmium and lead, and exposure to these metals via smoking. Environmental Monitoring and Assessment. 137 (1): 481-493.

20 Canfield, R.L, Kreher, D.A, Cornwell, C, Henderson, C.R Jr. (2003). Low-level lead exposure, executive function, and learning in early childhood. Child Neuropsychol. 9:35–53.

21 Perkins, M, Wright, R.O, Amarasiriwardena, C.J, Jayawardene, I, Rifas-Shiman, S.L, Oken, E. (2014). Very low maternal lead level in pregnancy and birth outcomes in an eastern Massachusetts population. Annals of epidemiology. 24 (12): e915.

22 Jedrychowski, W, et al. (2006). Exposure to Environmental Tobacco Smoke in Pregnancy and Lead Level in Maternal Blood at Delivery. International Journal of Occupational Medicine and Environmental Health; Heidelberg. 19 (4): 205-210.

23 Bahl, V, Weng, N.J.H, Schick, S.F, Sleiman, M, Whitehead, J, Ibarra, A, Talbot, P. (2016). Cytotoxicity of Thirdhand Smoke and Identification of Acrolein as a Volatile Thirdhand Smoke Chemical That Inhibits Cell Proliferation. Toxicological sciences: an official journal of the Society of Toxicology. 150 (1): 234-246.

24 Abusalah, A, Gavana, M, Haidich, A.B, Smyrnakis, E, Papadakis, N, Papanikolaou, A, Benos, A. (2012). Low Birth Weight and Prenatal Exposure to Indoor Pollution from Tobacco Smoke and Wood Fuel Smoke: A Matched Case–Control Study in Gaza Strip. Maternal and Child Health Journal. 16 (8): 1718-1727.

25 U.S. Department of Health and Human Services. (2006). The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General: Secondhand Smoke: What It Means To You. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health.

26 Järup, L, Berglund, M, Elinder, C.G, Nordberg, G, Vanter, M. (1998). Health effects of cadmium exposure -- a review of the literature and a risk estimate. Scandinavian Journal of Work, Environment & Health. 24 (1): 1-51.

27 Kim, Y, et al. (2013). Prenatal lead and cadmium co-exposure and infant neurodevelopment at 6 months of age: The Mothers and Children's Environmental Health (MOCEH) study. Neurotoxicology. 35: 15-22.

28 Tong, V.T, Dietz, P.M, Morrow, B, D'Angelo, D.V, Farr, S.L, Rockhill, K.M, England, L.J. (2013). Trends in smoking before, during, and after pregnancy--Pregnancy Risk Assessment Monitoring System, United States, 40 sites, 2000-2010. Centers for Disease Control and Prevention (CDC). MMWR Surveill Summ. 62 (6):1-19.

29 Centers for Disease Control and Prevention. (2017). Vital Signs: Disparities in Nonsmokers' Exposure to Secondhand Smoke—United States, 1999–2012. Morbidity and Mortality Weekly Report 2015. 64 (4):103–8.

30 Willers, S, Attewell, R, Bensryd, I, Schütz, A, Skarping, G, Vahter, M. (1992). Exposure to environmental tobacco smoke in the household and urinary cotinine excretion, heavy metals retention, and lung function. Arch Environ Health. 47:357–363

31 Willers, S, Schütz, A, Attewell, R, Skerfving, S. (1988). Relation between lead and cadmium in blood and the involuntary smoking of children. Scand J Work Environ Health. 14: 385–389

32 Apostolou, A, Garcia-Esquinas, E, Fadrowski, J.J, McLain, P, Weaver, V.M, Navas-Acien, A. (2012). Secondhand tobacco smoke: a source of lead exposure in US children and adolescents. American journal of public health. 102 (4): 714-722.

33 Jung, S.Y, et al. (2015). Association between secondhand smoke exposure and blood lead and cadmium concentration in community dwelling women: the fifth Korea National Health and Nutrition Examination Survey (2010–2012). BMJ open. 5 (7): e8218

34 Cross, D. (2015). How Third-Hand Smoke Ruins Your Home. Retrieved from http://www.movoto.com/blog/real-estate-tips/third-hand-smoke/

35 Centers for Disease Control and Prevention. (2017). Lead. Retrieved from https://www.cdc.gov/nceh/lead/



36 Tellez-Plaza, M, Navas-Acien, A, Caldwell, K.L, Menke, A, Muntner, P, Guallar, E. (2012). Reduction in Cadmium Exposure in the United States Population, 1988-2008: The Contribution of Declining Smoking Rates. Environmental Health Perspectives. 120 (2): 204-209.


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